Multiplex transmitter.



Patented Dec. 21, 1909. 2 SHEETS-SHEET 1.

J. J. COMER.

MULTIPLEX TRANSMITTER.

APPLIoATIoN FILED APB. 7, 1909.

J. J. COMER. j MULTIPLEX TRANSMITTER. APPLIOATION FILED APB. 7, 1909.

943,915. `Pmientea1)'@..21,1909.

Z y ZSHEBTB-SHEET 2. 519.3 qu im ya Leg @a 50 505 m n H L 1 if Showdow- `sought to be attained.

`a graniophone disk, 'into undulatory alterf n arrnn s'rArEs PATENT OFFIOE.

JOHN J. COMER, oF BALTIMORE, MARYLAND, Ass'IGNoR To GEORGE R. WEBB, IOE

, BALTIMORE, MARYLAND.

MULTIPLEX TRANSMITTER.

Specification of Letters Patent.

Patented Deo. 21, 1909.

Application ined April 7, 1909. serial No. 488,431.

To all whom it ma-y concern: I

Be it knoitn that I, JOHN J. Conan, al citizen of the United States, residing at I Baltimore, in the county of Baltimore and i Sta-te 'of Maryland, have invented certain l new and useful Improvements in Multiplex E Transmitters; and I do declare the follow- I ing to be a full, clear, and exact description g of the invention, such as will enable others i skilled in the art to which it appertains to make and use the same. reference being had i to the accompanying drawings, and to the letters and ligures of reference marked thereon, which form a part. of this specification. My invention relates to transmitters for use in the transmission of vibrations, suoli i for instance as the telephone transmission of sound vibrations. It. is particularly adapted for the transmission of musical vibrations, especially7 Where the vibrations are taken from a record. It is not howeveri confined to the illustration given but ini scope comprises Whatever use to which it| ma)v be applied Where the same'results are It has for its object to transform the' transmitted vibrations into undulatory al- L ternating electrical currents Whose variation in value corresponds to the original vibrations. For illustration, it transforms 'the y vibrations made upon a record, for instance,

nating electrical currents Whose variation in value will correspond to the original vibrations from vvhich the record is made. The transmitter is multiplex in form Orly character, and the invention is based on the discovery which I have made by a number of experiments' that the amplitude of the vibrations recorded on disks is a number of i times greater, say from-ten to..forty times greater. than granular carbon will properly respond to,'and this has led me to devise a multiplex transmitter which wlll` successfully produce the desired reduction of the amplitude of vibration to give the results lsought. The form ofthe transmitter which have found to give the-best results comprises, broadlyr stated, a lever vvlnch serves as an inertia. bar which is supported so as to have a vertical and a lateral movement, and carrying at one end a v1brator provided with a tracer to receive the vlbrations from a record, and a second lever connected at one end with the vibrator and at the Aother rear end in any suitable manner, say by 119 end with the electrodes of the transmitter supported from the inertia bar toward its rear end, the vibrations received by the vibra-tor from the record in the amplitude and frequency derived from it being transmitted to the lever connected with the electrodes land by said lever and inertia bar reduced in vibrator in one direction a reduced resistance is produced in tvvo of the carbon receptacles and an increased resistance. in the i alternation, become alternately positive and negative, and an undulatory alternating current whose variation corresponds to the original vibration made upon the record, is discharged over the subscribers line.

The foregoing arel some of the principal features of the invention, although there are other features, all of which Will be hereinafter indicated and described and then sought to be clearly defined by the claims, reference being had to the accompanying drawings forming a part hereof, in .which- Figure l is a side elevation of the transmitter; Fig. 2 is a plan view of the same; Fig. 3`a. vertical section on a central line. between the transmitters; Fig. 4 a cross section on the line 4-4 of F1 2; Fig. 5 a front View of the grou o individual transmitters forming a portion of the multiplex transmitter, with the electrode actuating lever and inertia bar in cross section; Fig. 6 a side view of Fig. 5 with two of the carbon holding cups in Section; Fig. 7 a font. view of the vibrator andf its knife e ge supporting late; Fi 8 a ront view of the knifeedg) plate; zignd Fig. 9 a diagrammatic view of the circuit.

In the drawings, the numeral -l designates what will be termed an inertia bar formed, say of metal, and pivotally connected at its a,pivot ypin2, to`a post-3 so as to have'a vertical movement, the lower part of the post being cylindrical so as to` flt in, a bracket or other support (not shown) attached to a wall or otherwise, so as to be free to turnv laterally, the inertia bar thus being capable of moving vertically and laterally. To the front end .of the inertia bar is attached a vibrator which may beo'f the type ordinarily used in connection with gramophone disks and consisting of a plate 1 having knife edgefbea'rings 5 and side lugs 6 to which are attached the side spring arms 7 of a vibrating plate 8 'from which extends a post 9 to which is connected by a thumb screw l0 a needle or tracer 11 designed to trace or follow the undulations of the record. This vibrator I support fromi lbar and has its upper end attached to the transmitting lever by a ,screw 1,5,.there 'being preferably elastic 'washers 16 at the point of attachment, and ,the end of the lever being preferably provided with a metallic cap 17 the transmitting lever prefere ably belng made of wood. Against the opj posite edges of the strip 13 rubber washers 18 are caused to bear,the same being held in place by set screws. 19 passing through arms 2O extending from' the inert-ia'J bar. rlhese washers serve as dampers so that while the strip is yielding or resilientit is steadied orgiven firmness in its vibrations. I have found that the best results are attained if th e length of the strip from the point of its attachment to the transmitting lever to the point vof its attachment to the vibrator is approximately one and one-half tunes as great as'the length of the vibrating member from the point of' attachment of vthe strip thereto to \the end of the needle designated a spider 22 fulciumed by pivots 23 and 24 to the overhanging arms 25 "of aflwhich contacts with the rec-ord.

.The rear end of the transmitting lever is connected with the carbon electrodes of the individual transmitters which are supported from or carried by the inertia bar at a point approximately two inches, moreA or less, from the rear end of the inertia bar, for the best results. Therear end-fof the lever is connected by a socket 2l what mayv be plate 26, preferably vof brass, and one of the pivots may be a threaded pin provided/with ajam-nut 27 to hold it to its adjustment.L VThe spider is formed with four lateral arms 28 to which are connected carbon buttons '29, 30, 31 and 32 constituting the front electrodes of four granulancarbon transmitters. The reari electrodes consisting ofthe carbon buttons 29a 30231c and 32d, are supported from the plate 26 'and insulated 33, and between the front and rear electrode' of each transmitter is the granular carbon 34 which is held in place by the cups therefromby a suitable insulating substance A 35`attached to the rear. carbon buttons and which may be of vfelt or other material. The plate 26 is supported from a plate 36, prefcerablyv of brass, by screws 37 insulated by material 38 from the plate, the plate 36 being. attached by a screw 39, o r'otherwise, to y The inertia bar serves to relievethe granular carbon in thev cups or receptacles of the transmitters from undue disturbancearising from vibrations derived through the tracer in Contact vwith the'revolving 'recordwhile at the same time the bar may-move laterally to conform to the movements given to the .vibrator 'by the undulations of the record, and may "have also a vertical movement `to accommodate any surface irregularities in Vthe plane of the record. The carbon transmitters being carried'by the inertia bar are `allowed the same movements as the bar withoutk the carbon granules being unduly disturbed, and even the low rate vibration set up in the incr-tia bar is to a large extent if not entirely prevented from being transmitted to the granular carbon by the cush-` ion in the form of soft rubber interposed between the rear 'plate of the carbon cups andthe plate supporting the same from the inertia bar. At the same time the amplitude of the vibrations derived from the record is so reduced by the transmitting lever of the electrodesthat they aretransformed into vibrations whose-variation in value corre; sponds to the original vibrations from which the record was made, and thus the vibrations are brought within the range of' the responsivecapacity of thelcaroon granules.

When this multiplex:` transmitter is used y in connection 4 with a'propenel'ectr'ic circuit there will be transmitted-over the line an undulatory electrical-current' whose. varia- -tion in value corresponds tothe original .vibrations from which a record was made.

7'an-d, thus the traxismitter is 'rendered o specialv value in the telephonie transmission fof musical or other :reproduced vibrations.V

I have devised a circuit specially Well adapted for use in connection with this transmitter and While claim is made to the same.

vet the transmitter described is not contined in its use to the circuit which Awill be udescribed. The circuit which I prefer is as follows. The front electrodes Q9 and 30 of the multiplex Itransmitter are legged to the branch ivire 41 of the line, and the front electrodes of the other pair of individual transmitters are legged to the branch ivire l2 of the line. The rear electrode 29a of one transmitter is connected bv Wire 43 Wit-h the vention.

rear electrode 32d of one dt the transmitters as shown7 and the Wire 43 is connected to a suitable source of current S. Therear electrode 31 of aiither transmitter is connected b v wire 44 With the rear electrode 30" of the remaining transmitter as shown and this wire ll is connected with the source of current.A Thus a transmitter of one pair of transmitters legged to the line is connected to one of the other pair of transmitters legged to line in such manner that movement impressed in oneV direction by the rccord on the tracer needle will produce a reduced resistance in the transmitters having the electrodes 29, 31 and an increased re sistance in the transmitters having the elec trodes 30. 32, thus sending the current over the line from the electrodes having for the time the increased resistance. AWhen `the movement of the tracer pin is in the opposite direct-ion the resistance will be reduced inthe transmitters previously having the high resistance but now having a reduced resista-nce and the current will be passed over the line from the transmitters which noiv have the increased resistance but previously had the reduced resistance. The points of discharge of the current over the line thus alternately change from positive to negative and an undulatory alternating current is discharged over the line whose variation corresponds to the original vibration recorded on the record.

A central station will be provided with any desired number of these multiplex transmitters, and each instrument will havea- -number of subscribers lines connected therewith, the line of each subscriber being provided With a suitable switch at the central station so that any particular subscriber or number of' subscribers, may be connected with the central lispensing station Whenever desired, tlie switch not being shown because it may be of anysuitabletype and does not constitute a` Having described my invention and set forth its merits, ivhatI claim is -1 A telephone instrument comprising a vibrating member to receive vibrations from .a record, an electrode to receive Yvibrations communicated from said vibrating member and. a lever for reducing the amplitude ot part of the present in! the vibrations transmitted from the vibrating member to the electrode, substantially as described.

Q. A telephone. instrument comprising a member to receive vibrations from a record, au electrode to receive vibrations communicated from said vibrating member, a lever for reducing the amplitude of the vibrations transmitted from the vibrating member to the electrode, and an inertia bar carrying said member, electrode and lever` substantially as described.

3. In a telephone instrument, a holder for granular carbon, a bar' carrying a tracer to receive vibrations from a record, and means for reducing` in amplitude and transmitting to the carbon in the holder vibrations derived from the record.

4. In a telephone instrument, a holder for granular carbon, and means for reducing in amplitude and transmitting to the carbon in the holder vibrations derived from a record.

A, telephone instrument including an inertia bar and a lever connected therewith for reducing the amplitude of received vibrations duringtheir transmission by the instrument. substantially as described.

6. A telephone instrument including a laterally movable inertia bar carrying a vibration receiving member, and a lever connected with said bai', for receiving vibrations and reducing their amplitude of vibration after being received, substantially as described.

7". A telephone instrument including a laterally and vertically movable inertia bar carrying a vibration receiving member, and a lever connected with said bar, for receiving vibrations and reducing their amplitude of vibration after being received, substantially as described.

S. A telephone instrument including an inertia bar carrying a vibration receiving member, a reducing lever carried by said bar, and a resilient connection between said lever' and the vibration receiving member carried by the inertiaJ bar, said parts cooperating to receive and reduce the vibrations derived through the vibration receiving member, substantially as described.

9. A telephone instrument including an inertia bar carrying a vibration receivinv member, a reducing lever carried by said bar, a resilient connection between said lever and the vibration receiving member, and cushioning dampers acting upon said resilient connection, said parts cooperating to receive and reduce the vibrations derived through the vibration receiving member,

`substantially as described.

v A brations,r substantially as described.

i A3o ber to increaseand reduce the lresistance in inertia bar, a plurality of individual trans- .mitters carried by said bar, and a lever capavnected Withfsaid oscillating member and in the individual transmitters in alternation, reciprocally to the received vibrations, substantially as described.

11. A telephone instrument, including an ble of responding to received vibrations and operating to increase and reduce the resistance in the individual transmitters in alternation, reciprocally to the received vibrations, substantially as described.

l2. A telephone instrument, including an inertia bar, a plurality of individual transs mitters carried by saidbar, a cushion intertelephone'instrument,- including an inertia bar, a -plurality of individual transmitters carried by said bar, an oscillating memberconnected With electrodes of the individualA transmitters, and a lever concapable of responding to received vibrations, and operating through said oscillatingmemthe individual transmitters in alternation, reciprocally to the received vibrations, substantially as described.

PLA telephone instrument, comprising;

rality of individual transmitters supported upon the inertia bar, and a reducing lever connected at one end With the vibration reelectrodes of the individual transmitters,

'40 y ceiving member of. the inertia bar and with said lever operating to transmit to the electrodes of the individual transmitters vibrations received from the vvibration` receiving member of the inertia bar, reduced in amplitude, and increasing and reducing the resistance in the individual transmitters in alternation, responsively to the received vibrations, substantially as described.

15. In a telephone instrument, a group of transmitters, a circuit in which the transmitters are included, some of the traiisniitters being in one branch of the circuit and others in a separate branch, and each branch leading to line, means for increasing the resista-nce in the transmitters of one branch and reducing the resistance inthe transmit ters of the other branch, to discharge a positive and a lnegative current to line from the branches, in alternation, and means for reducing in amplitude and conveying tothe transmit-ters vibrations derived from a record.

In testimony-whereof I affix my signature in presence of tWo Witnesses.

JOHN J. COMER.

Witnesses:

CARY D. HALL, Jr., WM. H. MARTIN. 

